浅谈iOS开发中方法延迟执行的几种方式

http://www.jianshu.com/p/6ed28a29b391

Method1. performSelector方法

Method2. NSTimer定时器

Method3. NSThread线程的sleep

Method4. GCD

公用延迟执行方法

- (void)delayMethod{ NSLog(@"delayMethodEnd");}

Method1:performSelector

[self performSelector:@selector(delayMethod) withObject:nil/*可传任意类型参数*/ afterDelay:2.0];

注：此方法是一种非阻塞的执行方式，未找到取消执行的方法。

程序运行结束

2015-08-31 10:56:59.361 CJDelayMethod[1080:39604] delayMethodStart2015-08-31 10:56:59.363 CJDelayMethod[1080:39604] nextMethod2015-08-31 10:57:01.364 CJDelayMethod[1080:39604] delayMethodEnd

Method2:NSTimer定时器

NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(delayMethod) userInfo:nil repeats:NO];

注：此方法是一种非阻塞的执行方式，

取消执行方法：

- (void)invalidate;

即可

程序运行结束

2015-08-31 10:58:10.182 CJDelayMethod[1129:41106] delayMethodStart2015-08-31 10:58:10.183 CJDelayMethod[1129:41106] nextMethod2015-08-31 10:58:12.185 CJDelayMethod[1129:41106] delayMethodEnd

Method3:NSThread线程的sleep

[NSThread sleepForTimeInterval:2.0];

注：此方法是一种阻塞执行方式，建议放在子线程中执行，否则会卡住界面。但有时还是需要阻塞执行，如进入欢迎界面需要沉睡3秒才进入主界面时。

没有找到取消执行方式。

程序运行结束

2015-08-31 10:58:41.501 CJDelayMethod[1153:41698] delayMethodStart2015-08-31 10:58:43.507 CJDelayMethod[1153:41698] nextMethod

Method4:GCD

__block ViewController/*主控制器*/ *weakSelf = self;

dispatch_time_t delayTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2.0/*延迟执行时间*/ * NSEC_PER_SEC));

dispatch_after(delayTime, dispatch_get_main_queue(), ^{
[weakSelf delayMethod];
});`

注：此方法可以在参数中选择执行的线程，是一种非阻塞执行方式。没有找到取消执行方式。

程序运行结束

2015-08-31 10:59:21.652 CJDelayMethod[1181:42438] delayMethodStart2015-08-31 10:59:21.653 CJDelayMethod[1181:42438] nextMethod2015-08-31 10:59:23.653 CJDelayMethod[1181:42438] delayMethodEnd

完整代码参见：

//

// ViewController.m

// CJDelayMethod

//

// Created by 陈杰 on 8/31/15.

// Copyright (c) 2015 chenjie. All rights reserved.

//

import "ViewController.h"

@interface ViewController ()

@property (nonatomic, strong) NSTimer timer;

@end

@implementation ViewController

- (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib. NSLog(@"delayMethodStart"); [self methodOnePerformSelector];// [self methodTwoNSTimer];// [self methodThreeSleep];// [self methodFourGCD];
NSLog(@"nextMethod");}

- (void)methodFiveAnimation{ [UIView animateWithDuration:0 delay:2.0 options:UIViewAnimationOptionAllowUserInteraction animations:^{ } completion:^(BOOL finished) { [self delayMethod]; }];}

- (void)methodFourGCD{ __block ViewController

weakSelf = self; dispatch_time_t delayTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2.0 * NSEC_PER_SEC)); dispatch_after(delayTime, dispatch_get_main_queue(), ^{ [weakSelf delayMethod];
});}

- (void)methodThreeSleep{ [NSThread sleepForTimeInterval:2.0];}

- (void)methodTwoNSTimer{ NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(delayMethod) userInfo:nil repeats:NO];}

- (void)methodOnePerformSelector{ [self performSelector:@selector(delayMethod) withObject:nil/*可传任意类型参数*/ afterDelay:2.0];}

- (void)delayMethod{ NSLog(@"delayMethodEnd");}

- (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated.}@end

文／笨笨编程（简书作者）

原文链接：http://www.jianshu.com/p/6ed28a29b391

著作权归作者所有，转载请联系作者获得授权，并标注“简书作者”。